Excellent work. My 65 Newport was a bit rusty on the passenger floor, but no rust-thrus, so I just painted. I get slight rain-water drips there from somewhere (windshield?) so cover the carpet w/ plastic in the rainy season.
I did the passenger floor on my 65 Dart, using sheet-metal from rockauto ($55). Mine wasn't so scary when cut out since the frame rail and tranny x-member are under there. I cut flush (much trial & error) and butt-welded, using my $90 Harbor Freight flux-wire welder. That was hard since it kept burning thru, even with a copper spoon behind. Next time, I'll lap-weld. I since read one can use a 20A light dimmer to lower the current and not burn thru (got one for next time). I covered my seams with Bondo Hair fiberglass and painted, so looks fine and only I know the holes are there. Before welding, I sprayed rattle-can high-zinc primer (some term "weld thru primer"), so all the places I couldn't paint afterwards are protected.